There exists an impetus to refine the accuracy of navigation piloting techniques now that electronic devices are capable of so accurately fixing a vessel's position. With this capability, it is imperative that a skipper be able to predict where the vessel is going to be in the immediate future with equivalent accuracy. Only in the last several years has the price and durability of electronic navigation gear allowed the presence of high accuracy navigation aboard anything other than the most sophisticated ships.
The use of electronic charts in disc or compact disc form and a television monitor display is current technology. An example of this usage is found in the Setliff et. al. patent No. 4,428,057. At present this technology is not well adapted to shipboard use, lacks the clarity of information available on the printed chart, and is alien to the navigator's habits and practices.
Up until recently there existed little expertise in the area of digitizing tablets for the conversion of X/Y coordinates into digital information. With the innovation of flexible, durable and inexpensive plotting boards, the conception of a plotting board for use by a large portion of the seagoing population is feasible.
There have been recent attempts to use plotting board technology to assist navigators. One such current device, commercially identified as the Yeoman Potter, employs a mouse type unit which is run over a chart adapted to be clipped onto a rudimentary digitized mat. The mouse comprises a small display window which reads out longitude and latitude inputted from an electronic navigator, such as LORAN. The mouse also includes a circular lens which attempts to locate the position on the chart. This device has many distinguishing, limiting features and disadvantages. Most significantly, its functions are severely restricted since it is capable only of one way communication; that is, it can only receive electronic signals, not input them. This shortcoming is most critical, for instance, in waypoint navigation where the use of pre-set waypoints, inputted into an electronic navigation system or autopilot, is desired. In addition, the mouse type unit is cumbersome to the average sailing vessel use. It is not natural for the navigator, who prefers and can more easily control pencil devices. The mouse's displays are limited and not easily readable or conducive to efficient viewing. The locating lens method is also inefficient. The configuration of the board in this device does not readily accept charts in seagoing conditions. It is not adapted to receive navigational charts and cannot read through a stack of charts.